Composite chromium and graphene oxide as saturable absorber in ytterbium-doped Q-switched fiber lasers.

In recent years, graphene and its compounds (e.g., oxides) have been used as saturable absorbers in passive Q-switched and mode-locked lasers, leading to the fabrication of compact pulsed fiber lasers. In this article, we study the operation of a Q-switched ytterbium-doped fiber ring laser based on a composite saturable absorber made of graphene oxide and chromium. We show that the addition of a thin layer of chromium can lead to pulse durations ranging from 3.5 to 9.4 μs and subsequently increasing the laser peak power.